Method of fabricating an inverted magnetoresistive head

ABSTRACT

A method of fabricating an inverted magnetoresistive head is disclosed. The method includes fabricating a writer. The writer includes a bottom pole positioned within a recessed substrate. The bottom pole is filled with copper coils and polymer. A write gap, a pole tip, and a top pole/bottom shield are fabricated on a portion of the polymer. A top surface of both the polymer and the write gap are planarized to provide a substantially smooth surface upon which a reader can be placed. The reader is fabricated on top of the writer and includes a first reader gap, a magnetoresistive element, a second reader gap, and a shield.

This application is in a continuation-in-part of commonly assigned U.S.patent application Ser. No. 08/206,007, filed Mar. 3, 1994, entitled"INVERTED MAGNETORESISTIVE HEAD", now abandoned.

Reference is made to the following commonly assigned application: U.S.patent application Ser. No. 08/484,696, filed on even date herewith, andnow abandoned, entitled "INVERTED MAGNETORESISTIVE HEAD".

BACKGROUND OF THE INVENTION

The present invention relates to a method of fabricating amagnetoresistive head for high frequency, high data rate, and high trackdensity applications, and in particular to a method of fabricating aninverted magnetoresistive head having the reader portion of themagnetoresistive head fabricated on top of the writer portion of themagnetoresistive head.

Standard magnetoresistive (MR) heads are fabricated with the writerportion fabricated on top of the reader portion. MR heads are used inmagnetic storage systems to detect magnetically encoded information froma magnetic storage medium or disc and to write magnetically encodedinformation to the storage medium. In a read mode, a time dependentmagnetic field associated with a transition from a magnetic storagemedium directly modulates the resistivity of an MR element. Inoperation, the change in resistance of the MR element can be detected bypassing a sense current through the MR element and measuring the voltageacross the MR element. The resulting signal can be used to recoverinformation or data from the magnetic storage medium.

Practical MR elements are typically formed using ferromagnetic metalalloys because of their high magnetic permeability, an example of whichis nickel iron (NiFe). A ferromagnetic material is deposited in a thinfilm upon the surface of an electrically insulated substrate or wafer.Changing magnetic fields originating from the magnetic storage mediumproduce a change in the magnetization direction of the MR element andthereby change the resistance of the sensor. This phenomenon is calledthe MR effect.

The element itself comprises a strip of MR material deposited on amagnetic shield layer to form an MR element. A series of depositions andetching processes form an active region from a portion of the MRelement. The active region is the area of the MR element that senseschanging magnetic fields from the magnetic storage medium. Changingmagnetic fields produce a change in the resistivity of the MR element.Typical resistivity changes are on the order of 0.5 percent to 2.0percent change. An upper magnetic shield acts as a barrier between theMR element and the surface of the magnetic storage medium to preventchanging magnetic fields associated with transitions passing by the headfrom linking back to the element. The magnetic shield also serves toprotect the element from receiving stray magnetic fields associated withtransitions from surrounding magnetic storage media.

Giant MR (GMR) sensors formed from GMR materials are the new line in thefamily of MR sensors. GMR sensors are formed from GMR elements, whichare multi-layered structures. These devices include either layers offerro-magnetic and non-ferro magnetic films for a similar set of films.Permalloy may or may not be part of the layered pattern. In GMR sensors,the change is resistivity can be in excess of 65 percent.

One problem which affects performance of MR heads is the degree to whichsurfaces in the head can be fabricated flat or "planarized." Inparticular, in prior art heads, the top shield of an MR sensor has a dipjust above the active region of the MR element. This degrades off trackperformance. Lack of planarization can also cause an electrical shortbetween various layers of the head, such as between the contacts to theMR element and the top shield or between the top shield and subsequentfabricated layers. In addition, the bottom shield is usually fabricatedfrom sendust or other high permeability magnetic materials, which isrelatively rough for a thin film. This relatively rough surface can alsocause shorting problems between the bottom shield and the contact film.Attempts at planarizing MR readers have focused on smoothing the bottomshield, planarizing the insulator above the MR sensor, or smoothing thetop shield. These steps take additional process time and can limitdesign flexibility.

Another problem which affects performance of MR heads is that GMR headsare susceptible to interdiffusion among the extremely thin layers of aGMR head during a polymer cure, even when a low temperature polymer cureis utilized. This interdiffusion can destroy the effectiveness of theGMR head.

SUMMARY OF THE INVENTION

The present invention is a method of manufacturing an invertedmagnetoresistive head for reading magnetically stored information from amagnetic storage medium. The method includes fabricating a bottom polein a recessed portion of a basecoat, which distal from an air bearingsurface of the magnetoresistive head. A polymer insulator and connectivecoils are positioned above the bottom pole. A top surface of the polymerinsulator is planarized. A write gap is fabricated on top of the topsurface of the polymer. A top surface of the write gap is planarized. Apole tip of magnetic high moment material is formed in the write gapproximal to the air bearing surface. A top pole/bottom shield isfabricated on top of the pole tip and the write gap. The top pole/bottomshield is planarized. A first reader gap is fabricated on top of the toppole/bottom shield. A magnetoresistive element is formed on top of aportion of the first reader gap proximal to the air bearing surface.Electrical contacts are fabricated on top of a top portion of the firstreader gap, the electrical contacts electrically connecting themagnetoresistive element to a region outside of the magnetoresistivehead. A second read gap layer is fabricated on top of the electricalcontacts and the magnetoresistive element. A top shield is fabricated ontop of the second reader gap. Finally, an overcoat of oxide isfabricated on top of the top shield.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a layer diagram view of the layer structure of a prior artmagnetoresistive head.

FIG. 1B is a layer diagram view showing the layer structure of the airbearing surface of a prior art magnetoresistive head.

FIG. 2 is a layer diagram view of the layer structure of a bottom poleof a writer of a magnetoresistive head prior to planarization.

FIG. 3 is a layer diagram view of the layer structure of a bottom poleof a writer of a magnetoresistive head after planarization.

FIG. 4 is a layer diagram view of the layer structure of a bottomportion of a writer showing a recessed channel in the write gap.

FIG. 5 is a layer diagram view of the layer structure of a writer of amagnetoresistive head.

FIG. 6 is a layer diagram view of the layer structure of an alternateembodiment of a bottom portion of a writer showing a recess channel inthe writer gap.

FIG. 7 is a layer diagram view of the layer structure of an alternateembodiment of a writer of a magnetoresistive head.

FIGS. 8A-8C are layered diagrams of the layer structure of an airbearing surface of a writer of a magnetoresistive head showing analternate method of fabricating a pole tip.

FIGS. 9A-9D are layered diagrams of the layer structure of the airbearing surface of a writer of a magnetoresistive head showing analternate method of fabricating a pole tip.

FIG. 10 is a cross-sectional view of the layer of the air bearingsurface of a writer of a magnetoresistive head.

FIG. 11 is a cross-sectional view of the layer structure of a completemagnetoresistive head.

FIG. 12 is a cross-sectional view showing the layer structure of the airbearing surface of a complete magnetoresistive head.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1A is a cross-sectional view of the layer structure of prior artmagnetoresistive (MR) head 10. MR head 10 of FIG. 1 illustrates astandard MR head having the writer portion of the head positioned on topof the reader portion of the head. MR head 10 includes basecoat oxide12, bottom shield 14, first reader gap oxide layer 16, electricalcontacts 18, MR element 20, second reader gap oxide layer 22, topshield/bottom pole 24, write gap oxide layer 26, polymer insulatorlayers 28a, 28b, and 28c, conductive coil layers 30a and 30b, and toppole 32.

Bottom shield 14 is deposited upon basecoat oxide 12. First read gapoxide layer 16 is then deposited upon bottom shield 14. Next, MR element20 is deposited in a magnetic field and patterned. MR element 20 is theportion of MR head 10 which senses a magnetic field associated with atransition from a magnetic storage medium during a read operation.Electrical contacts 18 are then deposited on MR element 20 and firstread gap oxide layer 16. Second read gap oxide layer 22 is thendeposited. The two oxide layers, 16 and 22, comprise the read gaps,inside which MR element 20 is fabricated. Next, top shield/bottom pole24 is laid down. Top shield/bottom pole 24 is normally utilized toprovide the top shield of the reader portion of MR head 10 as well asthe bottom pole of the writer portion of MR head 10.

Write gap oxide layer 26 is deposited, followed by polymer insulatorlayer 28a, conductive coil layer 30a, polymer insulator layer 28b,conductive coil layer 30b, and polymer insulator layer 28c. Finally, toppole 32 is deposited to complete the fabrication of MR head 10. Topshield/bottom pole 24 and top pole 32 provide the writing capability ofMR head 10 during a write operation. The number of conductive coils 30and polymer insulator layers 28 are determined by design and affect theinductance capabilities of the writer portion of MR head 10. Eachpolymer insulator layer, however, must be cured at temperatures between200° C. and 400° C. for varying lengths of time depending upon thespecific polymer. Only the lower half of this temperature range for thecuring process will avoid possible degradation of the magnetics of thereader portion of MR head 10. In addition, any cure temperature above200° C. will degrade the magnetics of a GMR device. This limits thechoice of polymers available as insulators for MR head readers.

As shown in FIG. 1B, MR head 10 is fabricated such that a top surface ofsecond read gap oxide layer 22 is not flat or planarized. The non-planarsurface of second read gap oxide layer 22 dictates that subsequentdeposited layers of MR head 10 are also not flat or planarized. Inparticular, top pole 32, which is covered by overcoat oxide layer 33,can be offset from the center of MR head 10, which can degrade thequality of tracks written from MR head 10. In addition, it is desiredthat each deposited layer of MR head 10 is flat or planarized to preventshorting of later deposited layers, thereby rendering MR head 10inoperable.

FIG. 2 is a cross-sectional view showing the layer structure near airbearing surface 52 of bottom pole 56 used in the present invention.Inverted MR head 50 includes base coat 54, bottom pole 56, polymerinsulator 58 having top surface 60 and dip 62, and conductive coils 64.

In one preferred embodiment, in order to fabricate inverted MR head 50of the present invention, bottom pole 56, formed from plated permalloy,is initially deposited into a recessed portion of basecoat 54. Therecess in basecoat 54 is formed through a combination of chemicaletching and ion milling. Polymer insulator 58 and conductive coils 64fill the portion above bottom pole 56. Conductive coils 64, which aretypically made of copper, can be positioned in polymer insulator 58 inone row, or as seen in FIG. 2, conductive coils 64 can be positioned ina plurality of rows. The number of conductive coils 64 and polymerinsulator layers 58 affects the inductance capabilities of the writerportion of inverted MR head 50.

As shown in FIG. 2, top surface 60 of polymer insulator 58 can besomewhat irregular. Dip 62 can arise due to loss of polymer volumeduring the curing process. In the present invention, it is critical thattop surface 60 of polymer insulator 58 be flat or planarized so that theremaining layers of inverted MR head 50 which are deposited on top oftop surface 60 are deposited on a flat surface. Thus, any rough, jaggedportions of top surface 60, including dip 62, must be eliminated.

As shown in FIG. 3, all jagged and rough portions of top surface 60,including dip 62, have been eliminated. This elimination is normallydone in one of two ways. First, the polymer material forming polymerinsulator 58 can be deposited such that top surface 60 is higher thanbottom pole 56. Top surface 60 can then undergo both a blanket reactiveion etch-back process and/or a chemical-mechanical polish until topsurface 60 of polymer insulator 58 is both smooth and level with bottompole 56. Second, the polymer material forming polymer insulator 58 canbe deposited having rough top surface 60 and dip 62 (shown in FIG. 2). Alayer of silica can be deposited such that the top surface of the silicalayer is slightly above bottom pole 56. Then, photoresist is depositedon top of the silica layer. When the photoresist hardens, it will beperfectly level due to surface tension. The photoresist and silica layercan then undergo a blanket reactive ion etch-back process that removesthe silica and photoresist at the same rate, until top surface 60 ofpolymer insulator 58 is both smooth and entirely flat.

As shown in FIG. 4, inverted MR head 50 further includes write gap oxidelayer 66 having top surface 68 and channel 70. Write gap oxide layer 66is deposited on top of top surface 60 of polymer insulator 58. Write gapoxide layer 66 can be formed from a variety of insulating materials,such as silica, alumina, or diamond-like carbon. Channel 70, locatednear air-beating surface 52, is then ion-milled into write gap oxidelayer 66 to define actual write gap 66a beneath channel 70. This allowsextremely accurate definition of the pole tip 72 (shown in FIGS. 5 and6). The reason is that the photoresist is deposited upon a flat surface,allowing more precise development of the features in the photoresistmask. Write gap oxide layer 66a at air beating surface 52 beneathchannel 70 has a height in the range of approximately 0.1 to 1.0microns, and preferably in the range of approximately 0.2 to 0.8microns.

As shown in FIG. 5, pole tip 72 is positioned at trailing edge 73 of airbearing surface 52 of inverted MR head 50. Pole tip 72 is an insertformed from a high moment magnetic material such as iron nitride orcobalt iron. A high moment magnetic material is capable of supporting alarger density flux than the permalloy used in standard MR heads. Thehigh moment insert forming pole tip 72 concentrates the magnetic fluxand allows writing of a narrow track.

The high momentum magnetic material forming pole tip 72 is either platedor sputtered into channel 70 until it is significantly higher than topsurface 68 of write gap oxide layer 66. The thickness of the high momentinsert depends upon the magnetic materials in the writer design. Typicalvalues for the thickness of the insert range from 0.5 to 2.0 microns,and typical values for the track width of the pole tip range from 2.0 to5.0 microns. In one preferred embodiment of the invention used forplated inserts such as cobalt iron (Co₉₀ Fe₁₀), a non-magnetic seedlayer such as nickel vanadium (Ni₈₀ V₂₀) can be used, which then becomespart of the write gap. The protruding section of high moment material isthen masked and permalloy is plated around it to obtain an approximatelylevel surface. The masking above the insert is then removed and theentire shield is plated as a unit to the desired thickness. The topsurface of the top pole 72/bottom shield 74 combination will very likelycontain irregularities, which are then removed by chemical mechanicalpolishing.

FIGS. 6 and 7 are layered diagrams of the layer structure of analternate embodiment of the present invention. FIGS. 6 and 7 are similarto FIGS. 4 and 5. Therefore, similar layers and elements have beenlabeled with identical numbers. As shown in FIGS. 6 and 7, polymerinsulator 58 is larger than that shown in FIGS. 4 and 5. Therefore,write gap oxide layer 66, deposited on top of polymer insulator 58, doesnot have a level top surface 68. In this embodiment, gap oxide layer 66is much thinner distal to air bearing surface 52 than in the previousembodiment. Top pole 67 is fabricated on top of gap oxide layer 66. Toppole 67 may be a high moment material. Next, oxide 75 is deposited andplanarized by methods previously discussed. Bottom shield 74 is thendeposited on top of top pole 67 and oxide 75.

The alternate embodiment shown in FIGS. 6 and 7 provide a gooddefinition zero throat. Good definition zero throat is necessary forproper performance.

FIGS. 8A-8C are layered diagrams of the layer structure of a secondalternate method of fabricating pole tip 72. In FIGS. 8A-8C, pole tip 72is plated or sputtered into channel 70. The pole material forming poletip 72 is then ion milled to provide the proper width of pole tip 72.Bottom shield 74 is then fabricated on top of pole tip 72 and topsurface 68 of write gap oxide layer 66. Bottom shield 74 is thenplanarized.

FIGS. 9A-9D are layered diagrams showing a third alternate method offorming pole tip 72. As shown in FIGS. 9A-9D, a layer of high momentmaterial is plated or sputtered on top of write gap oxide layer 66.These sides of pole tip 72 is then ion milled to provide the properwidth of pole tip 72. Lift-off photoresist layer 71 can be put on top ofpole tip 72 and additional oxide layer can be fabricated. Bottom shield74 is then be fabricated. Bottom shield 74 is then planarized.

FIG. 10 is a layer diagram showing air bearing surface 52 of a writer ofinverted MR head 50. As shown in FIG. 10, pole tip 72 is aligned abovebottom pole 56; with the critical portion of write gap oxide layer 66Alocated between bottom pole 56 and pole tip 72. The distance betweenbottom pole 56 and pole tip 72, which is the critical distance of writegap oxide layer 66 is in the range of approximately 1,000 to 10,000angstroms, and preferably in the range of approximately 2,000 to 8,000angstroms. In one preferred embodiment, bottom pole 56 has a height inthe range of approximately 2.0 to 4.0 micrometers, write gap oxide layer66 formed between top surface 60 of polymer insulator 58 and top surface68 has a height in the range of approximately 2,000 to 8,000 angstroms,pole tip 72 has a height in the range of approximately 5,000 to 20,000angstroms, and bottom shield 74 between top surface 68 of write gapoxide layer 66 and top surface 76 of bottom shield 74 has a height inthe range of approximately 1.5 to 4.0 micrometers.

FIG. 11 is a layer diagram showing the entire fabricated inverted MRhead 50, including both the writer and the reader portions of invertedMR head 50. Once bottom shield 74 has been deposited and planarized, theremaining layers of the reader can be deposited on the flat surface ofbottom shield 74. Deposition on a series of flat surfaces alleviatesshorting, which is a critical issue in standard MR heads.

Once the writer portion of inverted MR head 50 has been fabricated,first reader gap oxide layer 78 is deposited on top of bottom shield 74.In one preferred embodiment, first reader gap oxide layer 78 has aheight of less than 4000 angstroms. MR element 80 is fabricated on firstreader gap oxide layer 78 near trailing edge 73 of inverted MR head 50.MR element 80 may be a single film or composite film structure. Thespecific embodiment of MR element 80 does not affect the usefulness ofpresent invention. Electrical contacts 82 are then deposited, followedby second reader gap oxide layer 84, top shield 86, and overcoat oxidelayer 88. In one preferred embodiment, second reader gap oxide layer 84has a height of less than 4000 angstroms. In addition, a boundarycontrol stabilization layer, a permanent magnet stabilization layer,and/or an additional layer of contacts for inductive cancellation or lowcircuit resistance can be incorporated into the MR reader if necessaryfor a particular application.

FIG. 12 is a layer diagram of inverted MR head 50 showing both thereader and the writer. As shown in FIG. 12, bottom pole 56, top pole 72,and MR element 80 are aligned with one another. This invention improvesthe accuracy of the alignment of the MR sensor to the top pole, sincethere are only one or two intervening mask layers to complicate maskalignment, as compared to ten or more intervening mask layers in priorart non-inverted MR heads. The alignment of bottom pole 56, top pole 72,and MR element 80 is critical in forming an MR head which can bothprecisely read information from a magnetic storage medium and writeinformation to the magnetic storage medium.

There are several advantages of inverted MR head 50 of the presentinvention. First, precise definition of the top pole is achieved.Second, the distance between MR element 80 and top pole 72 issubstantially reduced over the prior art. This allows inverted MR head50 to write higher linear densities on the disc. Third, planarity of thetop pole allows the reader and the writer to be offset without the toppole having a dip in it, such as the dip of the prior art shown in FIG.1B. Fourth, use of sendust or other rough films for the top shield willnot cause shorting due to roughness, since the only film above the topshield surface is the overcoat. Fifth, building the writer prior tobuilding the reader allows use of high temperature curing polymers suchas polyimide and benzene cyclo-butene (BCB) without degrading the MRsensor magnetics or other properties. Sixth, building the writer priorto building the reader allows use of spin valves or giant MR sensorssince high temperature polymer cures could cause interdiffusion amongthe extremely thin layers of giant MR sensors or spin valves, thusdestroying their effectiveness. By having all high temperature curescompleted before the reader portion is built, few restrictions areplaced on the use of giant MR and/or spin valves sensors. In particular,the materials for the reader and writer can be optimized independentlyof each other to a much greater extent than the prior art.

Although the present invention has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention.

What is claimed is:
 1. A method of manufacturing an invertedmagnetoresistive head, the method comprising:fabricating a bottom polein a recessed portion of a basecoat distal from an air bearing surfaceof the head; positioning a polymer insulator and conductive coils abovethe bottom pole; planarizing a top surface of the polymer insulator;fabricating a write gap on top of the top surface of the polymer;forming a pole tip of high moment magnetic material in the write gapproximal to the air bearing surface; planarizing a top surface of thewrite gap; fabricating a top pole/bottom shield on top of the pole tipand the write gap; fabricating a first reader gap on top of the toppole/bottom shield; fabricating a first reader gap on top of the toppole/bottom shield; forming a magnetoresistive element on top of aportion of the first reader gap proximal to the air bearing surface;fabricating electrical contacts on top of a portion of the first readergap, the electrical contacts electrically connecting themagnetoresistive element to a region outside of the invertedmagnetoresistive head; fabricating a second reader gap on top of theelectrical contacts and the magnetoresistive element; and fabricating atop shield on top of the second reader gap.
 2. The method of claim 1wherein the step of fabricating a bottom pole further comprises:platingpolymer into the basecoat.
 3. The method of claim 1 wherein the step ofplanarizing the top surface of the polymer insulator furthercomprises:reactive ion etching the top surface of the polymer insulatoruntil the top surface of the polymer insulator is substantially smooth.4. The method of claim 1 wherein the step of planarizing the top surfaceof the polymer insulator further comprises:polishing the top surface ofthe polymer insulator with a chemical-mechanical polish until the topsurface of the polymer insulator is substantially smooth.
 5. The methodof claim 1 wherein the step of planarizing the top surface of thepolymer insulator further comprises:depositing a layer of silica on topof the top surface of the polymer insulator; depositing a photoresistlayer on top of the silica layer; and reactive ion etching the silicalayer and the photoresist layer until the top surface of the polymerinsulator is substantially smooth.
 6. The method of claim 1 wherein thebottom pole is made of a plated permalloy.
 7. The method of claim 1wherein the write gap is formed from silica.
 8. The method of claim 1wherein the write gap is formed from diamond-like carbon.
 9. The methodof claim 1 wherein the write gap is formed from alumina.
 10. The methodof claim 1 and further comprising:planarizing a top surface of the toppole/bottom shield.
 11. The method of claim 1 wherein the step offorming a pole tip of high moment magnetic material in the write gapproximal to the air bearing surface further comprises:ion-milling achannel into the write gap proximal to the air bearing surface; platingthe pole tip of high moment magnetic material into the channel such thata top surface of the pole tip is above a top surface of the write gap;and ion-milling a first and a second side of the pole tip to provide aproper width of the pole tip.
 12. The method of claim 1 wherein the stepof forming a pole tip of high moment magnetic material in the write gapproximal to the air bearing surface further comprises:ion-milling achannel into the write gap proximal to the air bearing surface;sputtering the pole tip of high moment magnetic material into thechannel such that a top surface of the pole tip is above a top surfaceof the write gap; and ion-milling a first and a second side of the poletip to provide a proper width of the pole tip.
 13. The method of claim 1wherein the step of forming a pole tip of high moment magnetic materialin the write gap proximal to the air bearing surface furthercomprises:fabricating a first write gap layer on top of the top surfaceof the polymer; plating the pole tip on the top surface of the firstwrite gap layer proximal to the air bearing surface such that a topsurface of the pole tip lies in a first plane; ion-milling a first and asecond side of the pole tip to provide a proper width of the pole tip;fabricating a lift-off photoresist layer on top of the pole tip;fabricating a second write gap layer on top of the first write gap layerso that a top surface of the second write gap layer lies in the firstplane; removing the lift-off photoresist layer; and fabricating a thirdwrite gap layer on top of the second write gap layer and the pole tip.14. The method of claim 1 wherein the step of forming a pole tip of highmoment magnetic material in the write gap proximal to the air bearingsurface further comprises:fabricating a first write gap layer on top ofthe top surface of the polymer; sputtering the pole tip on the topsurface of the first write gap layer proximal to the air bearing surfacesuch that a top surface of the pole tip lies in a first plane;ion-milling a first and a second side of the pole tip to provide aproper width of the pole tip; fabricating a lift-off photoresist layeron top of the pole tip; fabricating a second write gap layer on top ofthe first write gap layer so that a top surface of the second write gaplayer lies in the first plane; removing the lift-off photoresist layer;and fabricating a third write gap layer on top of the second write gaplayer and the pole tip.
 15. A method of manufacturing an invertedmagnetoresistive head, the method comprising:fabricating a bottom polein a recessed portion of a basecoat distal from an air bearing surfaceof the head; positioning a polymer insulator and conductive coils abovethe bottom pole; fabricating a write gap on top of the polymer insulatordistal to the air bearing surface and positioned on top of the bottompole proximal to the air bearing surface; forming a top pole on top ofthe write gap; fabricating an oxide layer on top of the top poleproximal to the air bearing surface; planarizing a top surface of theoxide layer and a top surface of a portion of the top pole distal to theair bearing surface; fabricating a bottom shield on top of the oxidelayer and the top pole; fabricating a first reader gap on top of thebottom shield; forming a magnetoresistive element on top of a portion ofthe first reader gap proximal to the air bearing surface; fabricatingelectrical contacts on top of a portion of the first reader gap, theelectrical contacts electrically connecting the magnetoresistive elementto a region outside of the inverted magnetoresistive head; fabricating asecond reader gap on top of the electrical contacts and themagnetoresistive element; and fabricating a top shield on top of thesecond reader gap.